High-pressure steam-engine



usaran s'rxrus 'Partnr orrIoE.

i BENJAMIN CRAWFORD, OF PITTSBURGI-LPENNSYLVANIA.

' `I-IIIGrI-I-PIRESSURE STEAM-ENGINE.

minish the power consumed in working the` condensing apparatus of steamengines, lessen its bulk and the cost of constructing it withoutdiminishing the power of the engine. The attainment of this object haslong been a desideratum, more "especially -in engines used in propellingvessels, because every pound saved in the weight of the engine addsproportionally to the capacity of the vessel for carrying freight, andby increasing her buoyancy lessens the resistance of the water to hermotion and enables her to sail faster with a given consumption ofl fuel.In so much has it been the object of river Steamers to obtain cheap andlight engines that they have, on our western rivers,

long since dispensed with the use of the condensing apparatusaltogether.

`My invention consists in shutting off the communication between thecylinder and the condenser an instant before the steam escapes from thecylinder when the piston has made its stroke, at the same time makingprovision, by means of a valve placed in the exhaust pipe, for the steamto escape into the atmosphere without resistance, which escape continuesas long as the elastic force of the exhaust steam is above theatmosphere, which is but a moment of time, when the communication isagain opened to the con-` denser. Egress to the air being at the sameinstant closed by the operation of the `valve in the exhaust pipe, thepiston travels in a vacuum in the same manner as in the ordi- 4narycondensing engine. By this operation no matter how great the pressure ofsteam in the cylinder when the exhaust takesplace there will only be acylinder full of s team at the pressure of the atmosphere to condense.Thus if the engine is working at full stroke with steam of eightatmosphereswhich is no uncommon pressure for steamboats on the westernwaters-seven eighths of this steam would, by my improved plan,

Specification of Letters Patent No. 11,117, dated June 20, 1854.

be suffered to `escape into the atmosphere,

leaving only one eighth to condense; thereby reducing the size of thecondensing apparatus in about the same proportion, as well as in likemanner diminishing bulk, weight, and cost, and also the power requiredto work it, and this to any one conversant with the steam engine issufficient evidence of the importance of my invention.

The l great value of the objects I have sought to attain by means ofthese improvements has been so long known among engimade to secure themby other means. One

of these was essayed by myself and for `which I obtained a patent, datedthe seventh day o-f September, in the year 1844, but on trial, althoughit possessed some advantages,

I found it inadequate to produce the results obtained by thisimprovement. In stationary engines where the bulk and weight ofapparatus, although highly objectionable, is

less so than in marine engines, it has been proposed torelieve the maincondenser partially of its duty by means of a supplementary condenser inwhich the heat evolved by the steam was applied to economical uses, suchas the boiling the works in distilleries orbreweries. So far as the twoobjects of boiling by the steam and the condensation of the steam arecompatible up to that point the supplementary condenser will relieve themain condenser, but when the liquid to be heated in the supplementarycondenser reaches the boiling point the main condenser would be requiredto perform full duty, just as if it was not at anytime assisted by asupplementary one. Under these circumstances `the size of the maincondenser could neers that numerous attempts have been not bediminished, for unless it was relieved all the time of aportion of theduty of condensing, it might as well not be relieved at j whereas theother contrivance, in addition to the ordinary condenser of full` size,and which at times has, as stated, to do full duty, has a supplementarycondenser of greater or less bulk, which at times relieves the maincondenser, more and at other times less, but

never allows the steam to escape through it by a free passage into theatmosphere. This therefore involves a more bulky condenser than isordinarily employed, while mine in- 'volves one less, bulky, and this isthe difference not only between my present condensing engine and that Ihave just described, but it is also the differencebetween it and allothers, including the one mentioned which I patented in 1844;, whichcould not be diminished in bulk, as I expected, because that p rtion ofthe steam which I 'suffered to es' mounted by` a valve-chest and exhaustpipe (B) made in any of the well known forms. The exhaust pipe (B)terminates in a Valvechest (F), in which a communication with thecondensing chamber (I) is opened and closed by a valve (c) operatedbythe toes (e e) of a rock shaft through a lever (Gr) andy valve stem(d), constructed and arranged in any well known or convenient manner. Onthe upper side of the exhaust pipe a communication opens with theatmosphere through the pipe (C), which may pass through the reservoir offeed water to heat the same. This communication at a point near theexhaust pipe is fitted with an escape valve (b) that opens outward, andwhich may be opened by the pressure of the steam from within when theexhaust valve is opened and closed by the pressure -of the atmospherefrom without when the condenser is open; or it may be opened and shutmechanically at the proper time wit-hout resistance by motion derivedfrom any of the moving parts of the engine; but whether it be opened andshut by the reciprocal action of the steam and atmosphere or by theengine it must be opened the instantthe exhaust valve of the engine isopened, to let that portion of the steam which is above the pressure ofthe atmosphere escape, and when this has been accomplished thecommunication between the exhaust pipe (B) and the condenser is openedby. raising the valve (c) as the entrance to the condenser, when theescape valve (ZJ) should` shut to prevent the air from rushing in andvitiating the vacuum. lThese conditions continue until the pistonreaches the end of the stroke, vwhen the valve at the entrance of thecondenser is closed, so that upon the eduction valve at construction ofcondensers in all their parts,.-

is well known, I have not deemed any milf;` nute description of the onerepresented here necessary. For the same reason I have omitted todescribe the construction of the cylinder and piston, the valves withtheir seats and the chambers in which they are placed and the pipes withwhich they are connected.

I have described but a single mode of arranging my improved condenserwith respect to the engine and but one plan of colnstructing it, butitis obvious that its construction and arrangement may be as various asthat of the steam engine itself without the least departure from theprinciple of my invention, and I contemplate making all the changes o-fthe character above indicated that may be found expedient in adapting myimprovement to different circumstances.

Having thus explained the nature of my invention, and the manner inwhich it may be applied I would state that an engine is described in theMech-@nids Magazine, vol. 36, pp. 33 to 36, for a purpose similar tothat of my invention, where the exhaust steam escapes against thepressure of a spring. This forms no part of my invention, but

What I claim is- The method of producing a vacuum in condensing enginesby allowing a part o-f the exhaust steam to escape into the atmospherewithout resistance by a flap valve as described before the condenser isopened and then condensing the remainder by o-pening the communicationbetween the cylinder and condenser whereby the weight, bulk, cost, andexpense of vworking the condensing apparatus are diminished, and thepower and eticiency of the engine are increased l Witnesses: Y

A. B. SToUGHToN, JOHN L. SMITH.

